This multidisciplinary program is concerned with mental retardation and related disorders, both with regard to pathophysiological mechanisms and possible ameliorative or prophylactic measures. One component focuses on defining EEG and Evoked Response features of retarded subjects. A second component is concerned with basic cellular aspects of neurophysiology as pertinent to mental retardation. A third is concerned with improvement and longitudinal evaluation of intensive care for the high-risk human neonate. A fourth component involves studies of social behavior in monkeys and quantitative behavioral testing methods in monkeys. This latter component includes social separation and other methods for creating animal models for certain aspects of mental retardation.